Controlling apparatus for highway crossing signals



April 16, 1935. H. A. THOMPSON 1,998,175

CONTROLLING APPARATUS FOR HIGHWAY CROSSING SIGNALS Filed June 16, 1931 2 Sheets-Sheet 1 I H G I INVENTOR. E912. H,H,T/vonwp50/7,

By @VLW #4 ATTORNEY.

April 16, 1935. H. A. THOMPSON ,1

CONTROLLING APPARATUS FOR HIGHWAY CROSSING SIGNALS Filed June 16, 1931 2 Sheets-Sheet 2 y 11; E F l :2.

Slo w Picli u 32 I X Y J Slow clvup Fig? 4. v INVENTOR I Patented Apr. 16, 1935 v UNITED STATES -rArEaNT s;or.F -I-;c1-:

' GONTROLLINGAPPARATUS"FOR HIGHWAY CRU'S SING SIGN ALS I Howard A. Thompson, Edgcwood,IPa.,sassignor. to

'.ThelUnion1Switch.-.& Signal Company, SwissvaleJPa a corporation of Pennsylvania.

jfApplicatiom-zlnneilfi, 1931, Serial No. 544,729

. --32.Claims. (015246-430) lay-invention relates to controlling apparatus ea-ch ofwvzhiclr'is associated-with a track: relay R Jorhighway crossing signa1s',- that is,-to-apparatus having =.a:corresponding exponent-and each of foriithe controlof signals whichareplaced atin- WhiCI'li'CODTzIOISQ. time element relayK'which, in

. tersections of railways and highways'for the purturn; controls .theoperation' ofthe signal S.

5-pose of warning users of the highway-when a J'Normally; that isto'say'whenthesection Z-G' 5 train-isapproaching a crossing; Y .is unoccupied/thetrackrelays'R. are all ener- One ofthe features of my inventionis the progized by virtueioi the. track circuit in-which they vision .of'apparatus for preventing a continued .areconnected in. series. The slow-releasing reoperation of-a highway crossingsignal in the event lays L are also alt-energized by: virtue of circuits '10 that a train-should stop within-a-control-section which. receive energy from a source'havingter- -10 "forisuch signalbefore it reaches the crossing or .tminals a: .andxy'and which include front contacts in: the event that atrainhaving once set the 5, E and Z i of-the track relays R ,;R andRfi resignal in operation by entering the signal control v:spectively. .The, slow-releasingfrelays J- are also sectionishould back out of such section. "Another .allen'ergized. by circuits which include front con- 15 feature. of my invention is the provision of appatacts 8;:9 and Hlof the track relays-R R and R odying my-invention. Fig. 2 ista similar 'view -of miles per hour,: thel'complctionv of. a stickcircuitifi;

'ratus for causing a signal to be operatedfor ap- "respectively. Under these conditions the signal S proximately the same length of time when a high is ineffective.

. speed train-isv approaching the crossing .as when 'Iwill assumethat an eastbound trainsproceed- .a low speed trainis approaching the crossing. in'g toward:.thercrossinglHpasses the' point 'Zand 2o I'will:descri-be four forms ofiapparatuslembod'y shuntszthe track relayRRcontact 'l 9. of which will .ingxmy invention, and'will' then point out. the "then open.themickupcircuit' for. relay J I will novel features thereof in. claims. also assume; that relay J isso constructedthat if 1 In. the. accompanying: drawings, Fig.v 1 isxa diaan'eastlcoundtraincrnovesthrough section- Z-fiA tgrammatic .view .of one form of-.-.apparatus'em-. atsa's'speed iof,zfor.exarn nle, not less than sixty another formof apparatusembodying my invenafor this relayby backicontact 9 of. track relayR -.tion. Fig. 3 is a similar viewio-f still another form- :when-theitrainfentersisection 'A-+B will be just in ofrapparatus'constructed in accordance with the time to prevent contacts i l and M of relay J from :present invention. Fig.4 is a similar view of a opening.

3o =fourthform of apparatus constructed in-accord 'Therefore if: the trainirnoves'rthrough section fiance with the present invention. a ZA ata speedioiinotuless thansixty'imiles' per -Similar reference charactersrefer to similar hourythefdeenergization'of relayiR -when :the parts in each of the several views. train 'reaches:..pointrA willzcompletean operating :Referring to the drawings, and with particular circuit forzsignalz-s .passing :from terminal x, 33 reference to Fig. 1 thereof, apparatus constructed through contacti iioffrelay'J ,.contact l 5 ofirelay so in' accordance. with my invention is shown'in corn- R contact i5110f relay Raicontact it ofrelaylR "bination with a stretch of railway trackX which contact 2210f relay .Rfitback-contact'2 i of'time comprises rails i and l and which is intersected *elementfrelay-K, .anditheimechanism of signal S :by a highway H protected bya signal S ofany touterminal: y. :.S ignal1-S,:i'Which is here indicated preferredrtype. The rails i and l are-divided sa'sahighway crossing..bell,=would, therefore, start 40 by insulated joints 2 to form-a main section'Z-G ringing. r and the rail l is subdivided bysimiIar joints 3 Atrftheisarnel time thatithea-operating' circuit is into series of relatively short'intermediate sec- :completediforisignal S, time element relay K 'tions' ZA, A-B, B-C, CD andDG. Atrack becomes energized by a :circuit which follows 43 battery 'd is connected across the rails l and l cthe cir'cuitijust traced for signal S as far-as con- 45 adjacent the right-hand end of the section'Z-G, .tact='.22 .of relay R and thence-passing through as viewed in the drawings, and a track relay- R is 'theiwindingsof: relay K to terminal 4 Relay K connected-across.the rails i and i adjacent the ;is 0f .art pe .which..picks up slowly but releases left-hand end of this-section. Track relayslR 'quicklygand. is designed to respond, when ener- 5 -R B l-and R -are connected in series with'the gizedgonly-iat the expirationpf a time interval relay R by havi the terminals of their w nd ngs which is of sufiicient. duration topermit a train connectediwith the rail Icon opposite sides ofthe proceeding.at.ia'ipredeterminedminimum rate of .jointst; The apparatus also embodies a'plurality sspeed to traverse the length1of any oneof the eofslow-releasing relays L L; and L and a second sectionsibetweenpoints A'andrGl 'The energizap v fi n relays-J 'J a'nd J tionofirelay Kgas just"describe'd,"will nowherefore cause the back contact 24 of this relay to open and interrupt the signal circuit previously traced therethrough, if the train continues, without stepping, through section AB at a rate of speed not less than the minimum rate.

The opening of front contact 9 of relay R when the train enters section AB, breaks the pick-up circuit for relay J which passes from terminal m, through front contact 9, and the winding of relay J to terminal y. I will assume that relay J is so constructed that if an eastbound train moves through section AB at a speed of, for example, not less than fifty miles per hour, the completion of a stick circuit for this relay by back contact I of track relay R when the train enters section B-C will be just in time to prevent contacts l2 and I! of relay J from opening.

When the train enters section BC, the deenergization of track relay R. will open its front contact it, thus interrupting the circuit previously traced through this contact for signal S and time element relay K. The deenergization of relay R also causes its front contact 1 to open the circuit for the associated slow-releasing relay L controlled by this contact. At the expiration of a predetermined interval oftime, which is sufficient for relay K to become fully deenergized, relay L closes its back contact l8.

Therefore, if the train has moved through section AB at a speed of not less than fifty miles per hour, the deenergization of relay R when the train reaches point B, will complete a second operating circuit for signal S passing from terminal at, through contact I! of relay J contact [8 of relay L contact 19 of relay R contact 22 of relay R back contact 24 of relay K, and the mechanism of signal S to terminal y. This will cause the signal S to continue its operation. The signal S may be so designed that the relatively short interval, during which its operating circuit is open after the opening of contact N3 of relay R and before the closing of contact l8 of relay L willnot cause a noticeable interruption in its operation. A second circuit for relay K is also thus established, which causes this relay to start over again its operation for opening its contact 24.

The opening of front contact 8 of relay R when the train enters section B-C, breaks the pick-up circuit for J which is similar to the pick-up circuit previously traced for relay J I will assume that relay J is so constructed that if an eastbound train moves through section BC at a speed of, for example, not less than forty miles per hour, the completion of a stick circuit for this relay by back contact 6 of track relay R when the train enters section C-D, will be just in time to prevent contacts I3 and 20 of relay J from opening. When the train enters section C-D, the deenergization of track relay R will open its front contact I9, thus interrupting the circuit previously traced through this contact for signal S and time element relay K. The deenergization of relay R also causes its front contact 6 to open the circuit for the associated slow-releasing relay L controlled by this contact. At

the expiration of a predetermined interval of time which is sufficient for relay K to become fully deenergized, relay L will close its back contact 2 I.

minal 3:, through contact 20 of relay J contact 2! of relay L contact 22 of relay R contact 24 of relay K, and the mechanism of signal S to terminal y. This will cause signal S to continue its operation. A third circuit for relay K is also thus completed which causes this relay to start over again its operation for opening its contact 24.

When the train enters section D--G, the deenergization of track relay R will open its front contact 22, thus interrupting the circuits for signal S and time element relay K. The deenergization of relay R also causes its front contact 5 to open the circuit for the associated slowreleasing relay L controlled by this contact. At the expiration of a predetermined interval of time which is sufiicient for relay K to become fully deenergized, relay L will close its back contact 23, thereby completing a fourth circuit for signal S passing from terminal ac, through back contact 23 of relay L contact 24 of relay K and the mechanism of signal S to terminal y. A fourth circuit is thereby also completed for relay K.

When the train departs from section ZG, the track relays all become reenergized, and thereupon restore the apparatus to its initial condition.

It follows that if the train proceeds uninterruptedly toward the crossing H at speeds not less than those specified for the various sections, the signal will operate except for the periodic interruptions between the deenergization of the relays R and the response of the associated relays L. If the train should stop in any of thesections, the time element relay K will respond, at the termination of the predetermined time interval for which it is adjusted, and open its back contact 24, thereby interrupting the signal circuit previously traced through this contact. If the train, after stopping, should go ahead and enter the next section in advance, it will deenergize the track relay R associated with such section and interrupt the circuit for the relay K controlled by the front contact of such track relay. The deenergization of relay K will again cause the signal S to function as hereinbefore described. If, instead of going ahead, the train should back out of section ZG, such of the relays R as may have been deenergized will successively be reenergized in a reverse order and restore the apparatus to its normal condition without again i causing the signal S to function. This is because the front contacts of each relay R close before the back contact of the associated relay L opens, and consequently the relay K is maintained energized.

If, instead of proceeding through section Z-A at a speed of sixty miles per hour or higher, an eastbound train should move through this section at some lower speed, contact H of relay J would open before back contact 9 of relay R would become closed. Hence, although contact l5 of relay R. would become closed in the circuits first traced for signal S and relay K, these circuits would still be open at contact 14 of relay J Hencc'signal S would not be operated before the train arrived at point B.

If the train should proceed through section AB at a speed of fifty miles per hour or higher, signal S and relay K would become energized by the second circuit which was traced through contact I1 of relay J and contact N3 of relay L If, however, the train proceeded through section A-B at a speed of less than fifty miles per hour, contact l2 of relay J would open before back contact I of relay R would close. Hence contact control windin'g through flexible relay comprises tionary-winding-25 which is constantly energized 17' of-relay 21 would-:also *open, and would therefore prevent operation OP-si'gnaI S- and ener'gization of relay -K, although back Contact of relay 'L werclosed. 1

-If thetrain *shouldnow proce'ed throughsection'B C at -a-speed'of'forty miles-per hour or -hi'gher,;-signal S and relay -Kyvould become op- -era-tedby' the thirdcircuit traced through-com tact-20 ofrelay J and contact 2 I' ofrelay L 5 If, however, the train proceeded through section B- at a speed "of less than f forty miles per hour, "contact -13 of relay J 4 Would openmefore' back contact of relay R would become-closed. Contact -'ofre1ay J "would therefore also be opened and prevent cperati'on "of signal S "and "relay K, alt-houghf'hack contact-il i "of -r'elay L were closed.

SignalSwvillf however, be operated for a given "period" every time "relayL "becomes deenergized '"on account-of thejpresenceof'a ,traindn'section 'D"G, or when relayL becomes deenergize'd' for "any ctherreason.

SectionsZA;A-"-B andB -C may 'be ofequal "lengths, whilerelays J "J "an'd' J may 'be con- "structed to havedifferentperiods of release ac- "cording tothe minimum train speeds 'of sixty,

fifty "'and"forty"miles'. per "hour, "respectively. 'A "modification of this arrangement could provide relays 'J J and "J with 'equal periods'ofrelease,

' but with the "lengths of sectionsZ'A, 'A"-B and B C varied accordingltothe 'minimum train speeds of sixtyffifty and forty"miles"per hour,

"respectively; g g

The speed of a'i train moving through section ZA, A -B and B Cdetermineswhether or not "bell S shall ring twhenfthe train reaches points tion, and will continue toi' ring while-the train 'is'in each section unlessthe .train stops or is moving at' less than a given'minimurn speed which, 'for example; might befifteen milesi'p'er hour. The train speed at which the bell will stop ringing is determined by the time required "for slow pick-up relaysP of 'Figs. 2 and 3 and f relay'W ofFig. 4 to open' their back contacts.

IJWiththe forms of apparatus shown inFigs. 2'

- and 3 sections A 'B,'B"C,' CD, D'E and'E-F '-may be of equal'lengths. SectiOn'F- G should preferably be short. v I I TiWith each of the'four 'formsofapparatus shown, the bell will-stopv ringing "if a train remainslin a section long enough for a slow pickuprelay, such as relay'K of Fig. 1,'relay P of "Figs 2 and 3, and relay'W of Figi l, to open its back contact. V

"In'Fig;.-2, I have shown another form of apparatus constructed in accordance with "my invention. In this particular construction, I employ a series of transformers. T designated by "appro- 'priate exponents, andhaving'primary' and secondary windings aandb,respectively: "The pri- "'inary'a 'oftransformer T ;is5connected in series wlt-hj'the' track; relay R and thesecon'dary b of :transformer 'T "is connecte'dwith -the movable of a galvanometer relay lVI connections 25 andzi'p r 'This a-core d provided with a stabyyabattery 2?. The terminals of the primary winding-of each of the transformers T T T "T and -'I are connected with thcrail i on op- "positesides or theinsulated joints 3, and the secondaries of these transformersare connected in parallel with eachother and with-winding b "oftransformer T The apparatusalso-includes twot'neutral relays-N and'N and a slow acting *relay 'P whichQashere shown, is ofthe type which' releases quickly and picks slowly.

Undernormal "conditions, the track relay R is --energizecl-by its track circuit but winding ZS-cf the galvanometer-relay M, the neutralrelays N and" N and thetime'element relay-P are all deenergiz-ed.

With the apparatus in this condition, I will assumethat an" eastbound train, approaching the 'crossing 'H,'enters section A"G at A-and causes "the deenergization of track relayR This will complete a circuit passing-from terminal a: of a source of electric energy not shown in the drawings, through back contact-28 of track relay" R back contact 290i time element relay P, and'opersame source.

ating mechanism of signal S to terminal y of the This will cause the signal to operatejand warntraffic on thehighway H 'of the approach of the train. The train," aswell as shunting track relay R also shunts the'primary a of transformer T current in this primary a causes-amcmentary surge of'current'to be induced in the secondary i; of the same transformer,'flowing from left to right as shown in the drawings and ofsumcient magnitude to energize the movable control winding 25 ofthe galvanometer relay M momentarily. This completes a pick-up circuit for relay N passing from terminal :11, through back contact 28 of track relay R pfront contact 3% of 'relay' l /l, back contact 3| of slow pick-up relay P, back contact 32"ofneutral rela'y'N and winding of neutral relay N toiterminal y. This causes relay N to close its front contact 33.

As soon as the surge of current in the winding 25 of thegalvanometer relay M dies out, front contact of this relay opens and interrupts the pick-up circuit just traced'for relay" N However; immediately upon the opening of frontcontact30 of relay M and before back contact 34 of this relay has had time to close, aIpick-up circuit for relay N and a holding circuit for relay N is established passing from terminal 3:,"through "back contact 28 of rack relay R front contact -33"of relay N and the windings of relaysN and 'N in seriesto terminal y. As soon as back con- "tact 34 of relay M closes, a second pick-up circuit is established for relay N passing from terminal :r, through back contact 1' 28 of relayR front contact-33 of relay N winding of relay N and back contact .34 of relay M to terminal 11. 7 Both to permit front contact 35 of relay N to close. ;The..closing of'front contact'35 of relay N comterminalsofthe winding of relay N are now connected with terminal y with the result that relay N is shunted and so rendered slow-releasing.

This'delays the opening of front contact 33 of relay N for a time'interval of suflicient duration pletcs a stick circuit'forthis relay passing from terminaln'through backcontactifl of relay R back contact 3ilof relay M, front 'contact 35 of relay N winding of relay N ,--and ba'ck contact The (lying down of the 34 of relay M to terminal y. The energization of relay N establishes a circuit for the time element relay P passing from terminal a, through back contact 28 of track relay R front contact 36 of relay N and winding of relay P to terminal y, but relay P being slow acting, does not respond until a predetermined time interval has elapsed of a duration suflicient to allow a train, moving at a certain minimum speed, fifteen miles per hour for example, to enter section BC.

When the train enters section BC, the transformer '1 is shunted which causes the galvanometer relay M to become energized again momentarily, as hereinabove described, and to open its back contact 30. This interrupts the stick circuit for relay N previously traced through this contact, thereby causing the deenergization of this relay. The deenergization of relay N causes its front contact 36 to open, thus interrupting the circuit for relay P long enough to permit this relay, which is of the type that releases quickly, to become fully deenergized. The deenergization of relay N also causes back contact 32 thereof to close and consequently when relay M closes its front contact 30, the circuit for relay N previously traced through these contacts, is completed. From this point on, the cycle of operations hereinbefore described is repeated.

I will now assume that a train has entered one of the sections between the points A and G and also that the relay N is energized by its stick circuit previously traced and that the time element relay P is energized by virtue of its pick-up circuit but has not yet responded. Under these conditions, if the train should stop, the time element relay P will, at the expiration of the time interval for which it is adjusted, respond and open its back contact 29. This will interrupt the circuit previously traced through this contact for the signal S and cause it to discontinue its operation. If the train should now proceed into the next section toward G, it will shunt the transformer T for such section and will thus cause the energization of the galvanometer relay M which will open its back contact 30 and interrupt the stick circuit for relay N This will cause relay N to open its front contact 36 and interrupt the circuit for time element relay P which will again close its back contact 29 and reestablish the circuit for the signal S.

On the other hand, if the train, instead of proceeding, should back out of the main section A-G, it will successively permit the reenergization of such of the transformers T as may have been shunted thereby. The reenergization of any of the transformers, however, will tend to cause a surge of current in the circuit for the galvanometer relay M of an opposite polarity such as will tend to maintain the back contacts of relay M closed. As a result, the stick circuit for relay- N is not opened and the circuit for the time element relay P previously traced through front contact 36 of relay N is maintained intact. The signal circuit through back contact 29 of relay P therefore remains open. It may be desirable to connect an asymmetric unit 1" in series with the secondary of each of the transformers T so as to prevent the surge of current produced in the secondary b of any one of the transformers, caused by the shunting of its primary by a train, from dissipating itself in the secondary of another of the transformers, the primary of which has been and still is shunted by the same train;

Asymmetric units 1', arranged as shown, will also prevent surges of current in the reverse direction, from right to left, from forcing the contacts of relay M against their back points when a train backs away from crossing H.

It will be apparent from the foregoing that as long as a train proceeds uninterruptedly through the several sections at a speed not less than a predetermined minimum, the signal S will operate without interruption, but that if the train should stop or back out of signal control territory the operation of the signal will discontinue. In this respect the apparatus functions as an indication of the progress of a train approaching the crossing H.

In Fig. 3, I have shown another form of apparatus constructed in accordance with my invention in which I employ a polarized relay Q instead of the galvanometer relay M shown in Fig. 2. In this embodiment of my invention, if a train enters section AB, it will deenergize the track relay R and cause it to close its back contact 28, thus establishing the signal circuit previously traced. The train upon entering section A-B also shunts the primary of the transformer T and causes a momentary energization of the polar relay Q. This causes front neutral contact 31 of relay Q to close and establish a pick-up circuit for relay N passing from terminal 3:, through back contact 28 of track relay R front neutral contact 31 and normal polar contact 38 of relay Q, back contact 3| of time element relay P, back contact '32 of relay N and winding of relay N to terminal y.

The energization of relay N causes it to close its front contact 33. As soon as the surge of current in the circuit for relay Q dies out, front contact 31 of relay Q opens and interrupts the circuit just traced through this contact for relay N but a pick-up circiut for relay N is established, in series with relay N passing from terminal :10, through back contact 28 of track relay R front contact 33 of relay N and windings of relays N and N to terminal 1/.

As soon as relay Q closes its back contact 39, a second pick-up circuit is established for relay N passing from terminal as, through back contact 28 of relay R front contact 33 of relay N winding of relay N and back contact 39 of relay Q to terminal 1 Both terminals of the winding of relay N are now connected with terminal 3/ with the result that relay N is shunted and rendered slow-releasing. This delays the opening of front contact 33 of relay N for a time interval of sufficient duration to permit front contact 35 of relay N to close. The closing of this contact establishes a stick circuit for relay N passing from terminal at, through back contact 28 of track relay R back neutral contact 31 of polar relay' Q, front contact 35 of relay N and back neutral contact 39 of polar relay Q to terminal y. The

energization of relay N also causes front contact 36 of this relay to close and establish a circuit for time element relay P passing from terminal it, through back contact 28 of track relay R front contact 36 of relay N and winding of relay P to terminal y. If the train proceeds at a speed not less than the predetermined minimum, previously referred to, it will enter section B--C before the time element relay P opens its back contact 29 in the circuit for signal S controlled thereby.

When the train enters section BC, the transformer 'I is shunted which causes the polar relay Q to become energized again momentarily, as hereinabove described, and open its back contact 31. This interrupts the stick circuit for relay N previously traced through this contact, thereby causing the deenergization of this relay.v

The deenergization of relay N causes its front contact 361to open, thus interrupting the circuit to become fully deenergized, The deenergization of relay N also causes back contact 32 thereof to close and consequently when relay Q closes its front contact 31 the circuit for relay N previouslytraced through these contacts, is completed. From this point on, the cycle of operations hereinbefore described in connection with this particular form of my invention is repeated'.

If the train should back out of any one of the sections, it will permit the reenergization of the transformer for that section and. will so tendto causea surge'of current in the circuit for the polar relay Q. The surge .of current in such case, however, will be of opposite polarity to that caused by the shunting of the transformer and therefore this relay will open its normal polar contact 38..and closeits reverse polar contact 48. This establishes a branch path for the stick circuit for. relay N 7 throughreverse. polar contact 40=of relay Q and thusimaintains relayNl energized and the circuit for. relay P through front contact 360i. relay N intact, notwithstanding that backnormal contact Slwhich controls the main path for the stick circuit for relay N is subsequently opened. The time element relay P is thus maintained energized and the signal circuit through its backcontact 29 held open during the backing-movement of the train.

It may be desirable to connect an asymmetric unit 1' in series with the-secondary winding of each of the transformers T in order to-prevent the current generated in'any one of these secondaries frombeing dissipated in the other secondaries. Asymmetric units 1', if'used, will also prevent surges of current in the reverse direction from energizing relay- Q.-

In Fig; 4, I have shown apparatusconstructed in accordance witha still furtherrembodiment of my invention in which I employ an ammeter relay U, two neutral relays V and V andza-time element relay W which as here shown has a slow pick-up and a quick release, for'controllingthe.

signal S, and in which the track .Xis divided by insulated joints 2 to form a single unbroken section A-G extending the entire length of the signal control territory; The-relay U comprises the usualmovable coil 4| the opposite terminals of which are connected With'terminal posts 42 and 43 -by means of flexible connections 43b and 43 respectively, and which is mounted for oscillatory -move1nent' between the pole pieces 240f a-permanent magnet 45; The-on4! actuates an arm 46- one. end of which isv connected by a flexible connection 4! with a terminal post 48 and the other-endnof which'carriesa-contact 49 for en;- gagement with a contactfiliwhich is connected by; arflexible connection i with a'terminal post 52. The contact Ellis carried by a slide-53 mount? ed in a guideway 54 so that when the coil 4! is energized, the arm 45 will firstparry the contact 49 into engagement with the contact 59 and then as'the' current increases, will .move the contact and slide bodily in a clockwise direction, as viewed in the drawings;

contact 45 out of engagement with the'contact 50 and then engages a shouldertikon the slide 53' -track X= adjacent the point G, and the other When the current the coil 4| is interrupted, the arm id-first carries the terminal 43 of this coil is connected with one terminal' of a battery 55, the other terminal of which is connected through a resistor 5'5 with the rail l Lof'th'e track X'adjacent the point G.

In this apparatus, if an eastbound train enters section AG,' a circuit for coil4l will be completed, passing from one terminal of battery 56,

through resistor 51,,rail ,l, wheels and axles of thetrain, rail I terminal post 42, coil 4!, and terminal post 43 to the other terminal of battery 56. This will, cause the arm 46 to swingiin a clockwise direction. and move the contact 49 carried thereby into engagement with the contact'fiil, This will cause the signal S'to operate byvirtue of acircuit passing from a battery 58,

throughterminal post 48,1iexible connection 41,.

arm 46, contacts 43 -50, flexible connection 5|, terminal post '52, back contact 59 of time element relay W, and operating mechanism of signal S to battery 58; A circuit is also established,

passing fronrbattery 58, through arm 45 and.

contacts 49-5il .of relay. U; back contact Eilof relay V and winding of relay V to battery 58. The energization of relay V shunts the lefthand portion of the resistor 51"by establishing a circuit passingnirom battery 56, through front contact 51 of relay. V right-hand portion of resistor 51, rail I,- wheels and axlesof the train, rail l and coil4| ofammeter relay U to battery 56. This increasesthe current flowing in coil4l and causes the arm 46 and contacts id-59 to move forward a certain distance. The energization of relay V also causes the energization of relay V by virtue of a pick-sup, circuit passing from battery 58, through front contact 52' of relay -V and winding of relay V to battery 58. This causes relay V to close its front contact 63 which establishes astickcircuit for this relay, passing from-battery 58, through back contact 64 of time element relay W, front contact 63 of relay V and winding ofthis .relay'to battery 58. Theenergizationof relay V causes it to open its back contact 60 and interrupt the circuit previously traced throughsthis .contactsfor relay V This causes relay. V to open its front contact 6| and to interrupt the: circuit previously'traced through this contact which shuntedhthe lefthand position of the resistor 51, thereby increasingthe resistance to the current flow in the coil 4! and causing. the; arm..46c to move to the left and open contacts 49-58. This does not, however,- interfere with the operation of the signal S for the reason that a circuit'is now established forthe signal passingfrombattery 58, through front contact Ellof relayv back contact 59 of time element relay W, and operating mechanism for signal S to battery 58. The energization of relay V also causes it to close its front contact 65 which establishes apick-up circuit for time element relay W, but this relay, being adjusted to operate only after a predetermined time interval has elapsed, does not immediately respond;

Now if the train-proceeds at a speed not less than a predetermined minimum, it will decrease the resistance of the circuit includingrails I and i for the coil 4| so that the arm 46 will again move to the right and close the signal circuit through contacts 495c before the time element relay W functions. The time element relay W afterward responds and opens its back contacts 59 and 64,- thereby interrupting the circuit for signal sand the stick circuit for relay V respectively, previously traced through these contacts. The denergizationof relay'V immediately opens its front contact 65, thus interrupting the circuit for the time element relay W and causing this relay to close its back contact 59 which again causes the operation of signal S. The interval of time during which the circuit for signal S is thus interrupted is only that required for the front contact 65 of relay V to open and the back contact 59 of relay W to close. The deenergization of relay V also closes its back contact 60, thereby reestablishing the circuit for relay V previously traced. The apparatus is thus restored to its initial condition and the cycle of operations above described is repeated.

It will be noticed that if the train proceeds at not less than a given minimum speed, the operation of signal S is not interrupted when the signal circuit through the contacts 4950 is opened on account of the opening of contact 6| of relay V a second circuit for the signal being then established through back contact 59 of time element relay W and front contact 60 of relay V The design of the signal S may be such that its operation will be continuous notwithstanding the periodic brief interruptions in its operating circuits by relay W. If, however, the train should stop anywhere within section AB, the contacts 49-50 will not close, and therefore when the time element relay W responds and opens its back contact 59, the branch path controlled by front contact 60 remains open and the signal S will cease operation. If the train should proceed after stopping, the decreased resistance in the circuit for coil 4| will again cause the contacts 49-50 to close and reestablish the circuit for signal S.

Although I have herein shown and described only four forms of apparatus embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In combination, a stretch of railway track intersected by a highway, a signal for controlling traflic on said highway at such intersection, a time element relay for controlling said signal, and means controlled by a train proceeding uninterruptedly over said stretch for successively forestalling operation of said time element relay.

2. In combination, a stretch of railway track intersected by a highway, 2. signal for governing trafiic over said highway at such intersection, a slow-acting relay for controlling the operation of said signal, a track relay for controlling the op:- eration of said slow-acting relay, and means operable by a train at varying distances from such intersection for periodically controlling the operation of said slow-acting relay independently of said track relay.

3. In combination, a stretch of railway track intersected by a highway, a signal for governing trafiic over said highway at such intersection, a slow-acting relay for controlling the operation of said signal, a track relay operable by a train upon entering said stretch for starting the op eration of said slow-acting relay, and means operable by a train at predetermined time intervals for stopping and restarting the operation of said slow-acting relay.

4. In combination, a stretch of railway track intersected by a highway, a signal for controlling traflic on said highway at such intersection, a

slow-acting relay for controlling said signal,

means operable by a train at different locations in said stretch for energizing said slow-acting relay, and means controlledby said train operable means for causingthe deenergization of said slow-acting relay.

5. In combination, a stretch of railway track intersected by a highway, 9. signal for controlling traiiic on said highway at such intersection, a time element relay for controlling said signal, and means operable by a train at different points along said stretch for alternately rendering said time element relay effective and ineffective.

6. In combination, a stretch of railway track intersected by a highway, a signal for controlling trafiic on said highway at such intersection, a time element relay for controlling said signal, and means operable by a train at time intervals of predetermined duration for alternately causing the energization and deenergization of said time element relay.

7. In combination, a stretch of railway track intersected by a highway, a signal for controlling traflic on said highway at such intersection, a time element relay for controlling said signal, means operable by a train upon entering said stretch for causing the energization of said time element relay, and means operable by such train at predetermined distances from said intersection for successively causing the deenergization of said time element relay momentarily.

8. In combination, a stretch of railway track intersected by a highway, a signal for controlling traffic on said highway at such intersection, a time element relay for controlling said signal, a circuit for said time element relay, and means operable by a train at different points in said stretch for successively interrupting said circuit.

9. In combination, a stretch of railway track divided into a plurality of sections, a signal, a time element relay for controlling said signal, a circuit for said time element relay, and means associated with each of said sections for interrupting said circuit momentarily.

10. In combination, a stretch of railway track divided into a plurality of sections, a signal, a

time element relay for controlling said signal,

and means associated with each of said sections for periodically delaying the operation of said relay.

11. In combination, a stretch of railway track divided into a plurality of sections, a signal, a time element relay for controlling said signal, a contact device associated with each of said sections, a plurality of control relays controlled by said contact devices, a main circuit for said time element relay controlled by each of said contact devices, and a plurality of auxiliary circuits for said time element relay, each controlled by one of said control relays.

12. In combination, a stretch of railway track divided into a plurality of sections, a plurality of track relays connected in series and adapted to be successively deenergized by a train proceeding through said sections, a plurality of auxiliary relays each controlled by one of said track relays, a signal, a time element relay, a circuit for said time element relay controlled by each of said track relays, a circuit for said signal controlled by each of said track relays and by said time element relay, and a plurality of additional circuits for said signal each controlled by said time element relay and by one of said auxiliary relays.

13. In combination, a stretch of railway track divided into a plurality of sections, a signal, a time element relay for controlling said signal, a track relay associated with each of said sections,

esa- 175,.

relay, and a:pluralityyof. auxiliary circuits ion said time "element relayjeachcontrolled by a back contact-of one of said-auxiliary relays;

14." In combination, a stretch ofrailway track divided into aplurality ofsections, a signaLtatime A element relay for controlling said signal, a cir--- cuit for: said :time {element relay, a :track; relay associated with each of. said sections for controlling-:said circuit, and ,a-relay. controlled by:

each of-lsaid track relays for controlling-said :cir-' cuit jointly with theassociatedtrack relay.

15. In combination, a stretch of railway-trackv dividedinto a plurality of sections, a signal,- a time element relayior controlling said signal, a

track relay, associated with each of said sections for controlling said-time element relay, and a plurality of slow-releasing relayseach; controlled by-one of said track relays for controlling saidv signal jointly with said track relays;

16; In combination, intersected by a highway, a signalior controllingtraffic over said highway at such intersection,- a

plurality oftrack. .relaysarranged at intervals. along said track, aslowpick-uprelay, a circuit forsaidsignal including a front contactof each of said track relays and a slowtpickeup-relay, and a circuit-for saidzslow pick-up relay including said front contactsof said a track relays.

, 17. .In combinatiomastretch of railwayfltrack. intersected bya highway, a signal forcontrolling.

traffic over-.said highwayat such. intersection, a plurality of track relays along said track, a slownpick-uprelay, a plurality of slow-releasing relays; a .first. circuit for. said. signal controlled by said track relays andby said slow .pick-up relay, and Ya plurality of additional circuits for said signal each controlled by certain of said track-relays and by,-one of said slow-releasing relays.

18. In combination, a stretch of railway track intersected by a highway, a signal for controlling trailic over said highway at such intersection, a plurality of track relays arrangedat intervals along said track, an auxiliary relay associated with certain of said track relays, and a slow-acting relay controlled by said track relays and by said auxiliary relays for controlling said signal.

19. In combination, a stretch of railway track intersected by a highway, a signal for governing traflic over said highway at such intersection, a slow-acting relay for controlling said signal, an auxiliary relay for controlling said slow-acting relay, a control relay, a pick-up circuit for said auxiliary relay controlled by said control relay, a stick circuit for said auxiliary relay controlled by said control relay, and means controlled by a train at varying distances from said intersection for successively energizing said control relay.

20. In combination, a stretch of railway track intersected by a highway, a signal for governing traffic over said highway at such intersection, a slow-acting relay and a track relay for jointly controlling said signal, an auxiliary relay for controlling said slow-acting relay, a control relay, a pick-up circuit for said auxiliary relay controlled by said control relay, a stick circuit for said auxiliary relay controlled by said control relay, and means controlled by a train at varying a stretch of railway track back contact of said arranged at intervals distances. from said intersection forv successively energizing said control relay.

21.. In combination, a stretch of railway track intersectedby a highway, a signal for governing trafii'c over said highway at such intersection, a slcweacting relay and a track relay for jointly controlling said signal, an auxiliary relay for controlling; said-slow-acting relay, a control relay, apick.-up .circuit for said auxiliary relay controlled by-said control relay, a stick circuit for said auxiliary relay controlled by said control relay; and ,aplurality of track transformers arranged-atwarying distances from said intersectionior-successively energizing said control relay.

22.- In combination, a stretch of railway track intersected by a 'liighway, a signal for governing trafiic over said highway at such intersection, a slow actingrrelay for controlling said signal, an auxiliary? relay for: controlling said slow-acting relay, aipolar relay, apick-up circuit for said aux- I slow-acting relay iorcontrolling said signal, a

first-auxiliary relay for controlling said slowacting relay, a second auxiliary relay, acontrol relay, a pick-up circuit for said second, auxiliary relay controlled .by saidlcontrol relay, a pick-upv circuit .f or saidfirst auxiliary relay controlled by. said second. auxiliary relay, a stick circuit for. said. first auxiliary relay controlled by said control relay, and means controlled by a train vvat varyingdistances from said intersection for successively energizing said control'relay.

24. .In combination, a stretch of railway track. intersected by a highway, a signal for governing traificmzer.v said highway at such intersection, a slow-acting relay for controlling said signal, a. first auxiliary relay, a second auxiliary relay for controlling said slow-acting relay, a polar relay, a pick-up circuit for said second auxiliary relay controlled by a front neutral contactand a normal polar contact of said polar relay, a pick-up circuit for said first auxiliary relay controlled by a front contact of said second auxiliary relay, a

first stick circuit for said first auxiliary relay controlled by a back neutral contact of said polar relay, a second stick circuit for said first auxiliary relay controlled by a reverse polar contact of said polar relay, and means controlled by a train at varying distances from said intersection for successively energizing said polar relay in a normal direction when said train is approaching said intersection and for successively energizing said polar relay in a reverse direction when said train is backing away from said intersection.

25. In combination, a stretch of railway track intersected by a highway, a signal for governing traffic over said highway at such intersection, a control relay controlled by a train in said stretch for controlling said signal, a slow-acting relay for controlling said signal jointly with said control relay, a first auxiliary relay for controlling said slow-acting relay, a second auxiliary relay, a pick-up circuit for said second auxiliary relay controlled by said control relay and by said first auxiliary relay, a pick-up circuit for said first auxiliary relay controlled by said second auxiliary relay, a stick circuit for said first auxiliary relay controlled by said slow-acting relay, and means controlled by said second auxiliary relay for controlling said control relay jointly with said train.

26. In combination, an electrical conductor, an indication device, means for supplying current to said conductor, means for energizing said indication device when the current in said conductor increasesfand means for alternately energizing and deenergialng said indication device when said current ceases to increase faster than a given rate and for again energizing said device constantly when said current again increases.

27. In combination, a stretch of railway track intersected by a highway, a highway crossing signal for said intersection, a slow-release relay responsive to the speed of a train approaching said intersection so it remains closed if a train approaches at high speed but becomes open if a train approaches a lower speed, means controlled by relay for operating said signal when a train. moving at high speed arrives at a given point, and means for starting operation of said signal when a train moving at a lower speed arrives at a point nearer said intersection.

28. In combination, a stretch of railway track intersected by a highway, a highway crossing signal for said intersection, a plurality of slowrelease relays responsive to the speed of a train approaching said intersection, and means controlled by each of said relays for operating said ignal when a train arrives at a corresponding distance from said intersection.

29. In combination, a stretch of railway track intersected by a highway, a highway crossing signal for said intersection, a stick relay having a pick-up circuit which becomes opened when a train arrives at a given point and having a stick circuit which becomes closed if a train approaching said intersection arrives at a second point within a given period of time after arriving at said first point, and means controlled by said relay for controlling said signal.

30. In combination, a section of railway track including an insulated joint in one rail, a signal adjacent one end of said section, a track circuit for said section including a battery connected across the rails at one end of the section and a relay connected across the rails at the opposite end of said section as well as a second relay connected to the one rail around said insulated joint, a slow-release stick relay, 2. pick-up'circuit for said stick relay including a front contact of said first relay, a stick circuit for said stick relay including a back contact of said second relay, and a circuit including a front contact of said stick relay for controlling said signal.

31. In combination, a stretch of railway track one rail of which is divided by insulated joints into a plurality of successive sections, a plurality of transformers the primary winding of each of which is connected to said rail around a corresponding one of said insulated joints, a track circuit for said stretch including a track battery connected across the rails adjacent one end of said stretch and a track relay connected across the rails adjacent the other end of said stretch, an electrical device, a circuit comprising a plurality of branch paths each. of which includes a secondary winding of one of said transformers and which are in multiple with each other but in series with said electrical device, and a plurality of asymmetric units each of which is connected in a corresponding one of said branch paths to prevent current generated in each of said secondary windings from being dissipated in any of the other secondary windings.

32. In combination, a section of railway track, a source of current connected across the rails of the track adjacent one end of said section, a highway crossing signal, and means for causing operation of said signal when the magnitude of the current drawn from said source is increasing due to the shunting action of a train approaching the said end of the section and for stopping the operation of said signal when the the magnitude of such current ceases to increase due to the stopping of such train in the section.

HOWARD A. THOMPSON. 

